<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            height: 200px;
            width: 300px;
            background-color: yellow;
        }
        nav{
            color: red;
            width: 30px;
            height: 30px;
        }
    </style>
</head>
<body>
    <div class="box">div</div>
    <nav>3</nav>
    <script>
        
    </script>
</body>
</html>